It pays to check your mobile phone bill with a fine-toothed comb. My mobile phone provider tried to charge me more than $50 extra this month, claiming a discrepancy between the time I signed up for my new cap plan and the start of their billing period.

My argument was how would anyone signing up for a phone plan know the billing cycle of the provider? Also, surely the days unaccounted for were still covered by my previous plan? Their argument also made little sense because despite claiming I had not started my new plan until July 11 and that the billing cycle started July 8, they had charged me for calls from July 8.

Basically, I signed up for a $49 cap plan with several hundred dollars of included calls and texts, then they tried to give me less than half of what I was entitled to. The extra $50+ was supposedly to cover what I had spent in the four days I was outside the plan.

Pretty cheeky considering I have been a customer for more than 10 years and could easily have churned or stayed off contract.

They told me to go back to the store where I signed up and I said no way was I doing that. I asked them to calculate the $50+ in calls – anyone who has looked at a mobile bill will understand it is night on impossible to work out the true charges by the time they do calls, texts, credits, GST etc.

In the meantime I worked out I should have been entitled to about 90 per cent of my month’s included calls. Lo and behold, they worked that out too and decided the computer must have made a mistake. I will get the $50+ credit on my next bill.

The moral of the story is take the time to read your bill, preferably with a calculator. If it looks unnaturally high it probably is! The downside is you will need at least half an hour or more on the phone to sort it out. That’s preferable to the hour plus I spent on the phone to the bank during a recent series of calls to rectify a credit card billing problem but that is a story for another time!

Now if only I could get rid of the unsolicited spam SMS messages offering free ringtones.