Imagine the following situation:
A customer of a relatively high cost service asks a supplier for a full refund option bound to a specific condition that may or may not occur later in the process. The refund option isn't part of the standard supplier agreement. The customer signals that the refund option is a condition to move forward with the purchase of the service.
The supplier agrees to the refund option by email and tells the customer to refer to the email conversation in case the refund condition will be met, but provides their standard agreement template which doesn't include the refund option. The agreement additionally states that it supersedes any previous agreements. The customer signs the agreement in expectation that the supplier will stand by their word of offering a the refund option, even if it's not part of the signed agreement.
Has the customer still a claim on the previously offered refund option once the refund condition is met?
Based on the signed agreement I would say no, however, the refund option was a condition to move forward in the first place, so it may be seen as an attempt to defraud the customer, tricking them into signing something they didn't want. Also, what about false advertising?