Vodafone — Bill generated while porting out

Hi, I was using Vodafone Postpaid service for years and was paying bill on time then I started having network issues and nobody could reach out my number easily. I could not get any help from customer care hence i decided to port out. I got a call from Vodafone representative to request to cancel the porting out. I told him that i did not get any help since 3 months on network issues so he said he will take care of the issue and my bills will be waived off for next 6 months. I was using my cousin's corporate plan and never used their data service so always my bill amount was fixed i.e 352.82 Rs per month. I canceled the request and did wait for 3 days but still problem was not resolved so finally I ported out after paying my last bill. according my bill cycle I might have used their service less than 15 days before porting out. Actually I was having network issues so i have hardly made any calls. After a month I received bill of 1000 rs. I did not pay as i never received itemized bill for this one like usual. I asked for it but in return I get harassment calls and even my cousin who has nothing to do with it he gets such call till now. I don't understand if i ask for itemized bill they never provide it but they send me emails me and ask to pay. Stop Scamming people and making it complicated . you fail to provide good service hence i ported out. I was given waive off to cancel the porting out request which i did. On what basis that bill has generated? Why should i even pay?