No Feedback and slow ordering!

The fuel gauge on my car stopped working. So even though it is full its shows as empty. I took the car in last year november and they said they will order the part. I took my car in February for a service and they changed the part then. It worked for about a month and gave the same problem again. I informed them and they said they will order. I waited and went back a month later only to find new staff and no one seems to know about the order. This was in June. I went again end of July where the manager said the part was on order. I phoned a couple weeks later and couldn't get hold of anyone and the manager NEVER returned my calls. I phoned again today where the service lady says there was no part put on order. When I spoke to the manager hre keeps saying he's checking and that whole bunch of parts came through. He told me thw same thing last time. its been almost a year now and still the same problem!!!