Returned printer 3 times and still not sorted

5 months after purchasing an HP printer we changed the cartridges & the machine stopped working. I called HP who said I must return it as it needed new printer heads. Job was completed in 5 days only to have same problem when we got home. Returned again. Took 3 weeks this time and still not working when we got home. Returned a third time insisting they check cartridges as well & we wanted a new machine if not working after this. When went to collect, the machine was scuffed and the power cable was missing. We wanted it tested before returning home but they couldn't even find an extra cable in store. We left it there and were told the manager would call on the Monday (this was Saturday). We're still waiting for a call more than a month later. I've tried calling at least 10 times and if I get through, I get stuck on hold for repairs department. On the two occasions I've spoken to someone they couldn't help and took my details for the manager to call me back. Still no calls and manager apparently on leave!!! We haven't had a printer in over 6 months!