Change of rental plan

hello,
I am Shubham from Kolkata using Reliance postpaid gsm number 8100797971.I am using the pospaid facility since november,2013.I am using Rs.321 plan on this number my billing date is 27 of every month. I wanted to change the plan to Rs.199 from this month i.e from 27th september . I contacted the customer care on 24th september,they said they are unable to process my request due to their techincal upgradation task.I called on 25th repeatedly on 26th and 27th but the customer representative were unable to process my request due to their technical fault and from 27th september the system activated RS.321 plan on my number as usual.I called the customer care complaint number 198 to proccess my request and change the plan to 199 one.they said this isn’t possible from current billing cycle and wecan change the plan from 27th october.today i called the Secretariat office Reliance and explained the whole thing to Mrs.Shivangi Bhaley,she addressed the issue in a ludicrous way.I was very disappointed with the way she addressed the whole matter.
a very simple and straightforward question to Relaince,why shall the customer suffer and pay extra money(321-199=122+service tax)for your technical fault.
kindly look into this matter and help resolving it as soon as poosible
Thank you,
Shubham