Affidavit format

Hi Forum members, Need help on a format for a affidavit. Initially i was working via a proprietership firm and now have started a pvt. ltd company. Now i want to transfer the customers from proprietership firm to the company. There are few customers from whom there are some pending payments based on their old Purchase orders. To be able to invoice from the new entrity for against existing work orders one of my customer has asked to submit an affidavit to state that that the old firm is handing over the customer to the new entity and will not raise any further invoices from the old firm. I need the format for such affidavit.

Thanks in advance.