The worst restaurant

Last night I was in a restaurant [this would be 'correct', but it might be more natural to say 'Last night I went to a restaurant' or 'Last night I ate at a restaurant']. I thought that it would be nice but it wasn't. Starting with the food: it was too cold and drinks weren't cold enough. The food was unsavory and there wasn't information about allergens on the menu. It was the worst food I have ever eaten [some native speakers would naturally double-up "ever" and "before" here, but it is not strictly 'correct'].
The waiters were so unfriendly and weren't fast enough. They got all the dishes wrong. They were unfriendly and never smiled at us.
The cost of the meal was so expensive considering the low quality of the food and the slow service. We felt horrible because of the bad service and food. We won't recommend it and we won't go back again [or, instead of "go back", you could use "be back", but this would be more informal].

My perfect restaurant would be nice and charming. The food would be healthy and tasty. The service would be fast and the waiters would be located close to my house [this is grammatically correct, but odd - why would the *waiters* be close to your house???]. The quality-to-price would be reasonable and I would feel great being there.

The worst restaurant

The last night I was in a restaurant.> Last night, I went to a restaurant for dinner.
I thouthg that will be nice but didn´t.> I thought it would be a nice place to go to, but it wasn't.

Starting with the food, it was too cold and drinks weren't cold enough. > For a start, the food was too cold, and the drinks were not cold enough.

The food was unsavory and there wasn't allergen menu.> The food was unsavoury, and they do not even have an allergy menu.

It was the worst food I have never eaten before. > It was the worst food I have ever eaten.
The waiters were so unfriendly and weren't fast enough. > The waiters were very unfriendly, and the service was very slow.

The got wrong all dishes. They were unfriendly and never smiling us.> They got our order completely wrong, yet they were unapologetic and still unfriendly towards us when I complained.

The cost of the meal was so expensive to the low quality of food and to the slow service. We felt horrible because of the bad service and food. We won't recommend it and We won't back again.

> The cost of the meal was so expensive considering  the low-quality food and slow service they had given us.

My perfect restaurant would be nice and charming. > My perfect restaurant is one that is nice and charming.

The food would be healthy and tasteful. > And the food they serve has to be healthy and tasty.

The service would be fast and the waiters would be located close to my house. > The service has to be fast and the waiters friendly, and it will be great if the restaurant is nearby my house.

The quality-price would be reasonable and I would feel great being there.> Their prices must also be reasonable for the type of food they serve. If these criteria are met, I think I will enjoy my visit there.

> "Would" to indicate something that you can imagine happening. But, you are not doing that, you are just stating what you expect from a restuarent, not that there is none that you know of.

The worst restaurant

Last night, I was in a restaurant. I thought it would be nice but it wasn't. Starting with the food, it was too cold, but drinks weren't cold enough. The food was unsavory and there wasn't an allergen menu. It was the worst food I have ever eaten.
The waiters were so unfriendly and weren't fast enough. They got all the dishes wrong. They were unfriendly and never smiled at us.
The meal was so expensive for the low quality of food and the slow service. We felt horrible because of the bad service and food. We don't recommend it and we wouldn't go back again.

My perfect restaurant would be nice and charming. The food would be healthy and tasteful. The service would be fast and it would be located close to my house. The quality and price would be reasonable and I would feel great being there.