Do as written in the loan contract. What are you afraid of? At worst, just give them money. There is nothing to be afraid of. If you are afraid of being cheated, you can give them the next payment. If they insist that you pay first, they are not sure whether they can pay next time. This situation is mostly to cheat you of the upfront cost, so you must resolutely not give it. If you sue, let the court decide, and if the other party wins, you will be practical. So you don't have to sue them after being cheated.