Pathetic service from NRE

They billed me for calls that I never received on a number that I’m not using anymore and it was communicated with them and member I spoke to assured me they they would sort it out, today on 24/01/2024 I called to follow up and member was confused as to what I was referring to and again reassured me to sort out matter… after about 5-10 minutes he sent me an email stating they wouldn’t refund me the charges for the calls and forwarded me an email address of his senior to speak to which both of them were out of office and they would call me back but haven’t. Pathetic service from this company as they don’t want to account for anything and are very rude over the phone.