Terrible service and dishonest store manager

I bought a bed and a dining room set from Lewis on 6 months term. I asked who was then the store manager to work out a price for me should I pay the debt off over a period of three months which he had written the amount on my signed contract. I paid my last installment on the 25/03/15 when the new manager Jackie told me that the previous manager gave me the wrong amount, and I should provide her with my contract. She told me that she will consult with her senior managers and contact me, that never happened. I made numerous attempts to contact her during last week where I was constantly told that she was busy and There was one instance where my call was transferred to her and I could hear her speak, but she never spoke on the phone she just left me to hold on for her and eventually I hung up. I went to see her on the 4/04/15 and she advised me that the previous manager (Romeo Smith) will fix the account the same day. I have spoken to Romeo today and he said there is nothing he can do as he does not work for that store anymore and Jackie has to sort it out. I am disgusted that Lewis treat their paying customers like dirt. I feel like I am being punished for settling my debt.