Damage to my car - Horrific Service!

In December I had to have my window replaced by Glasfit Cresta. On replacing my window they damaged the inside panel of my door and the inside rubber of my window and then tried to hand the car off to me. I pointed this out to them and they said they would replace the rubber for me. It was agreed upon,between myself and the lady at reception that I would settle the excess once they have completed the job. Three weeks later I get a call telling me that they have received the rubber and I can bring my car in to replace it. I took my car in and after sitting there for an hour, they send the poor guy who needs to replace the rubber to tell me it's not the right rubber! Not one of the ladies working at reception even had the decency to come tell me this themselves! They then expected me to go to Renault myself and source the rubber! I declined and waited for them to get the rubber and call me again once they had it. I did not receive any calls since, and today Roy from the collections department calls me and tells me that if I do not pay by the end of the week they are handing me over! Still no rubber!! Pathetic!