Horrible service at Suzuki centurion

I brought my Suzuki jimny in for a shudder problem. They did what they do and everything we spoke, there was suddenly something new wrong with the car. They then made me pay upfront for the parts to be ordered and never got in contact with me again. Now 5 months later I'm back at the dealership and my part is not here and they say it's my fault. They also can't find the paper work of my payment or details of where my part is