It's a little late to get upset or angry about the lies. If you want to find out the truth, by all means call the guy. There are things you were responsible for checking before you handed over money. Like his size. If you want a large pony, then make sure they measure. If you don't know how to tell a horse's age, ask the vet to look.

Buying horses is a buyer beware market, it always has been. If you don't have the experience take along someone who can help you even if you have to pay them for their time.