Hathway Cable & Datacom — Hd set top box

I converted my normal set top box to hd set top box by paying 4500/- before around 20 days for which I have not received any receipt yet.while giving set top box the person told mi that cost is 4500/- and for one year hd pack is free and you don't have to pay charges for hd pack. Now when I go to hathway office in mulund east they told mi that the amount of 4500/- is included.one year charges of 2000/- and it is not free.
Secondly the picture quality is not good so I called hathway person to check the quality so he came today and I show him but he replied that the quality will not improve further.
Hence inspite of paying charges of hd pack if there is lack of picture quality what is the meaning of purchaising hd pack. I m very disappointed with the approach of hathway person that the quality of picture will be the same and there will be no improvement.
Hence I want to cancel the contract and return the hd set top box. Kindly give me refund of 4500/- at earliest.
Pl reply mi only email I'd nitinkarande.[protected]@rediffmail.com