Avis - Problems at Munich Airport

I prepaid a booking (on avis.co.uk) and collected the car at Munich Airport. I returned it today, on time.

The first car we were given had a broken wing-mirror motor so we were given a different car, so far so good.

I returned the car today and then the problems started;

1. There was no record of us having been given the replacement car, so it couldn't be checked in so I had to go back to the counter.
2. They then tried to charge me a couple of hundred Euro on top of the rental which at first I didn't realise but luckily spotted. They explained it was because I "had asked for an upgrade". I got that charge removed, "everything is now correct, Sir" but there was about 50 Euro remaining, so;
3. That was explained because I had returned the car late. I hadn't, but in "correcting" the previous mistake they changed the booking times. So I got this changed, "everything is now correct, Sir" but this left 20 Euro;
4. The 20 Euro charge was for winter tyres "we cannot remove that charge, Sir". Luckily I had my original voucher with me which specifically stated the tyre charge was included, so I got that removed as well.

So 4 invoices later, I finally got the correct receipt, the one which says the booking was pre-paid and I owe nothing.

Everything seems to have been sorted out now (just waiting for the credit card statement to check) but my question is, is this worth taking up with Avis, and if so should it be with the UK company or the Munich branch? How much influence does one country (where I booked) have over another country (where the car was hired from)?

Many thanks in advance, and I'm a regular customer of Avis in the UK and have no axe to grind!

I think it is worth raising the complain as some would qualify this as a fraud attempt. I had the same issue with Hertz in Canada and raised the issue with the head office, explaing that I felt the numerous attempts to cheat me as being a fraud. Interestingly it was also on a pre-paid voucher.

After a few e-mail exchanges and a threat to complain to the authorities, they "investigated" the matter with the branch (or franchisee?) and decided to refund the whole amount as a commercial gesture for the way I have been treated.

Based on this experience, I would say it is worth explaining the situation. I would do that to Avis Germany but if you are a regular customer in the UK, it could also be the best place. I think the european headoffice for Avis is in the UK anyway.