Advise

I bought a new car on the 27th May 2020 in east London vw and same day in the afternoon I noticed that the car seat is not adjustable and the handbrake is fault and reported that immediately. The only assistance they gave me is to take the car for repairs and they told me that they cannot replace it and give me a new car I signed a contract for. I am very much disappointed up until now the car is still with vw fir repaires and I do not have a car now but am expected to pay installments at the end of the month. Kindly advise on the matter