A strange one. I took my car to a local garage for a basic service, and was told it would be ready by the end of that day. Called up an hour before closure and was told that the car was almost ready, but I should come over at lunchtime the next day because they needed to sort the paperwork. Day 2 I go over as planned, the car is ready but the invoice is not. The garage are a bit sheepish about it and agree to give me my car back if I come back in the morning to get the invoice. Day 3 I go back to get the invoice, and it still isn't ready. I'm told to 'pop back in the week and see if we have it for you'.
From my perspective, I have my car back and I'm not out of pocket (yet), so in some ways it's no skin off my nose however long they choose to take to let me pay for the service. However, I'm not sure how much 'popping in' I can do, and they can't give me any indication of when the invoice would be ready.
Is the onus on me to keep reminding them until they can come up with the invoice, or should I just wait for them to get in touch? They seem a little flaky.