Almost 5 MONTHS of trying to get a simple part replacement/repair sorted

After 4 months of trying to have an item repaired we are still no closer to a resolution. The communication is seriously lacking with multiple calls daily / weekly / monthly going unanswered or returned. We have spoken to several staff ranging from reception, service department staff up to management. All promises of answers and feedback are unfulfilled and no one seems to be able to supply any information or care about resolving the issue. In addition due to them not sorting out the initial issue another element has been broken and we are now having to pay out more money to get this fixed. The amount of time and energy spent as a customer just trying to get feedback is exhausting. Amongst the shocking service they have also made internal mistakes regarding this repair and not even apologized for that. What does a customer have to do to have a simple repair completed?!