Legal notice from Office of Sole Arbitrator

I have been receiving a series of legal intimations, from the office of sole arbitrator engaged by my credit card bank, demanding payback of the total outstanding amount on my credit card. I have fair intentions of paying back the entire amount and I have already spoken with the local branch of the concerned credit card bank and got my total outstanding converted into EMIs (8 in total) and I have even paid 2 of them in timely fashion. I even have a letter from the bank stating that in consideration of the special circumstances I was facing, the bank is extending the time period within which I can payback the principal amount plus the accrued interest in EMIs. However this information was somehow not communicated to the bank's head offices in Mumbai and eventually the central recovery/legal team from Mumbai branch initiated legal proceedings to recover the outstanding amount from me. The latest legal notice, from a series of 3, requires me to be present at Mumbai to face some kind of trial within a week. I have already contacted all the customer support and grievance redressal channels offered by the bank but my problem has not been resolved. I have some questions : 1) Is it mandatory for me to be present in Mumbai on the stipulated date and time? What if I fail to appear? 2) What can I do to put an end to the legal solicitations (besides paying the outstanding amount in full) ? The arbitrator has not shared any of his contact details apart from his physical mailing address.