The fact that he keeps calling everyday in spite of your clear NO answer tells us that you are just dealing with an unstable individual. There is no rationalizing with or appeasing such an individual.
Offer him the option of a partial refund if he willing to first be outed on the boards for this behavior (He must be willing to admit to the behavior publicly first) otherwise tell him to bug off and add him to call block.
Under no circumstances should you allow yourself to be in an intimate compromised position again with this guy whether freebie or paid. If he can't rise to the occasion a second time he might just take it out on you.