Fight them with SKMM.

I also face same problem with you about this overcharging when you register a new First 38. I also paid RM40.30 during registration and then they charge me pro rated plus another RM38 advance. I told them I already paid the advance during registration. Drag for few months already. Always explain that the charges was correct. Then I asked them to compare with the lines I MNP to Celcom and why the billing did not have any advance payment charges. Finally last week they called me and said will refund back the RM38. I wait n see first la.

I also had a case with Digi whereby they used to promo cash back guarantee. When I register that time, they said cancel within 7 days to get RM50 back if your usage is below RM25. I cancelled within 7 days but after a while, they change the tnc to cancelling after 7 days. Of course they only refund me RM25.xx while deduct the usage. I fight a few months with them until they admit their wrongdoings. However the cheque still havent arrived after 4 months. I think I will fired a new email to them soon.

SKMM is like peace maker. It will keep track of the conversation between you and celcom as long as it's being done through SKMM site. Celcom would need to deal with your complain as long you didn't accept their story and keep pressing for a solution. Since skmm is also a body for governing quality of services provided by telco, any wrongdoings by telcos might be penalised.