We have a client to whom we have explained the whole Agile process, where he pays for each sprint (as billing cycles), and he agreed to it.
We are a new company and we don't really have a legal advisor. That being said, we are charging 50% of the billing cycle at the start, and 50% at the end; and the customer made the first payment before signing the contract. (The project has about 4 billing cycles so far).
Today we sent the contract for the first cycle, but the customer asked us to send a contract for the whole project. Since we are doing Agile development, we charge per cycle, meaning that each cycle's price might change depending on requirements, therefore there is no such thing as a "total price", but only estimations.
How do we [re]explain this to the customer?
PS: Yes, clearly we were not clear enough when explaining this the first time, so we want to re-explain it without sounding like we never told this about.
Considering the fact that he knows he payed just for the first cycle, how do we explain that others cycles are just an estimate? (The document describing each cycle had a disclosure that says: "Changes in requirement might cause price changes")