cheating

I bought are 1gb data bundle that last for 30 days last month on the 27 which is supposed to last till the February 27 to my suprise I checked my balance on the 25 afternoon I was left with 485mb and on the 26 I had none of my bundles when I called to find out what's going on I was advise that it ends on the 26 at 12 midnight which that is cheating cause it's 29 days instead of that 30 where by they don't even send you an sms to advice you. which is an inconvenience to me and is unfair to a customer