“He says we never serviced his unit”

This is what the product is for, so it is the fastest thing in it.

Search the customer or the site → open the placement → the History tab → find the date → Send record. The PDF carries the time the stop was completed, the serials serviced, the photos your driver took, the GPS line when he permitted location, and his name.

If it is going to keep happening with that customer, use Share history page instead. That gives them a live link to every record for that site, so the next argument never reaches your phone.

Recorded by you — SwapProof records service completion; it does not certify sanitation or regulatory compliance.