Pathetic Service!!! Taking twice time to do the job than promised

Pathetic Service!!!! I gave them my car due it its great service received 6 years ago and thought they would still be a great company to deal with. For that reason i had to request my Insurance Company to change the repair company to renew-it. I however was told by them they will finish the repair by 10-12 Working days from receiving the car and they have all the spares required. The time went past i kept calling them for feedback and they were going pretty ok with repair for the first week and half. then all of the sudden i am told that they are waiting for the parts and will get the repair done 10 working day from the parts receiving and there must be a communication error. After which they confirmed that they have received the part and all structural repair is done and it will go on painting section on 18th and I might not get the car on Friday but rather Tuesday knowing Monday is public holiday. I was also informed they will check if they can work over the weekend to fast track the process but got no confirmation. Come Tuesday I have been trying to get hold of them and eventually when I do I am informed that they could not repair a part and will be replaced, its available and they have got confirmation from the supplier and should be delivered by end of same business day and I will get a call with confirmation by the representative. I received no confirmation what so ever. When next day (24th March) trying to get hold of them had no luck till 11 am and I receive the mail indicating the estimated completion date moved to 9th April 2021 (additional 13 working days)). When contacted then get a chance to speak to relationship manager after 10 minutes holding on the phone, I am told that it was insurance’s fault that they approved for repair and thus it takes so long. Also she said that they can do the job but I will have to come back again as it will not be a quality work, THAT’S A SWEET THREAT. And I do not appreciate statements like that meaning I must give you additional 13 working days otherwise you will produce do a poor work. Now it fuels me that it takes them so long to realise that it needs to be replaced and once they do realise it will now take them additional 13 working days whilst the part is readily available. This proves that I have been misinforming along with the progress. They seem to have no worry of what is the client's condition; whether they have another car or not they just want to move in their pace. The relationship manager has asked me to give her till end of business and hopefully she will come up with a better plan. But truly I am not coming back to renew –it Bedfordview anymore if I do not get favourable timeframe to get the quality job- done.