Developer Creating Issues for Cancellation of Unit After Buyer Seller Agreement

Hi, This is to bring to your kind notice that I am facing some issues regarding property matter, which I had bought a long time back in Greater Noida. Due to many reasons (delay in project delivery, no amenities, no inhabitance etc) I do not want to retain the property and would like to cancel the unit. I have a Buyer-Seller Agreement (BSA) Signed with the developer not the sale deed yet. I took a CLP plan and have paid almost 90% of the amount. I got a possession letter in April'19 and builder asked for the remaining 5% payment. Also they've increase the size unnecessarily due to which the cost of the unit has gown up. I have plenty of mails exchanged to clarify queries and have asked relevant documents like OC, CC etc but builder haven't furnished it yet instead of that he is charging me 18% per annum delay interest since April 2019. Recently, to threaten me he sent a unit forfeit letter which says that a said amount will be deducted as a non-refundable charges due to non-payment of remaining amount. They have imposed unnecessary components in the forfeit charges along with earnest money of 10% which is mentioned in the BSA. Earnest money deduction is understood but rest of the components like Admin charges, Commission, Interest, Taxes etc is not clear and builder is not ready to provide any supporting document for the same. The worst part is that the builder is saying that until the unit is sold to third party they won't be refunding the remaining amount which according to me as per the finding is illegal. According to RERA recent rule the amount in case of cancellation should be refunded within 45days. So there are two issues - 1. I don't want to keep the unit anymore 2. The forfeit charges are unclear except earnest money 3. Builder is not furnishing proper documents for forfeit charges and no time frame to refund the remaining amount 3. No guarantee from builder to refund the remaining amount Could you please help in this subject and can you connect or take my case or push builder for arbitration? How much time or hearing this matter should take? Please help!