Sorry to have caught this thread so late!
My advice would be to avoid that restaurant in future simply out of principle. You've worked to earn your money, why should you spend it at a place that serves you tepid hairy food and then calls you a liar?
You wouldn't return to a garage that smashed in your car windows and then claimed it was like that when you dropped it off.
I have been served tepid food twice when eating in some of the chains (Hungry Horse, Wetherspoons) but never in a "gastro-pub" or a restaurant. Now, in the former two, your food is prepared by a cook or even bar-staff. But, at the latter two, your food will almost certainly be cooked by a chef. A chef once told me "The difference between a cook and a chef is about ten grand a year", but they seem to be able to use The Force to make food stay hot for longer than I can.
I was a waiter, full-time (graduates earn more than non-grads? not until they get a graduate job they don't!!
). It was a pretty classy establishment, around £50 a head for a 3-course meal (not including the price of the wine!). We were a non-tipping restaurant, instead we were paid a half-decent wage and expected to maintain standards without the lure of gratuities. The chefs were all masters of their art, and had all worked in Michelin-starred restaurants before coming to our place.
As a waiter, without a doubt the most common complaint was with regards to food temperature.
Serving temperature, like any other dimension of the gastronomic experience, is a matter of personal taste. And like all others (salt, spice, other seasonings) it really does detract from the final experience if you over or underdo it. So, the chefs have to make the food appeal to the majority of the clientel even with regards to temperature.
Some foods retain heat better than others. Bacon thrown into a cool salad will almost certainly cool down before it reaches the diner, however a casserole will still be too hot to eat. And if you ask for your steak to be blue, it won't take long to cool down once it gets to you, so less talking and more eating please!
Most of the complaints were that the food wasn't hot enough. Now, judging by the steam coming off the plate when I put it down, I knew their food was plenty hot enough! But, they obviously liked third-degree burns on their palate and served their food in such a manner at home!
However, the fact remains that you are a patron paying a fair sum for a meal you wish to eat. If your food is not hot enough, ask the waiter to do something about it.
I must also caution you to be polite, quiet and friendly to them unless you wish be served what is referred to in the trade as a "Winner".
This is a delicacy reserved only for those who like to shout and stamp and kick up a fuss
Too much butter on his crumpets, my a**e... Oops, flashback