We request all disputes be filed on our form, but as Carey said, it is not required by the customer. For record keeping, we do require our branches to fill in our form if a dispute is received by phone or if the customer brings in his/her own written dispute (if this happens, the customer's written dispute is attached to our form when submitted to Card Services). The same is true if the dispute is received by email. We also request signatures wherever possible, but don't require them - we don't even require them for provisional crediting purposes.
I reject your reality and replace it with my own.