Money management problem?please help?

I have this bad habit that I can not save money or i'd better say manage or handle my money properly. I get ripped off often....when I write down my expenses I lose a lot of money because people easily can charge me for the same service that for example somewhere else charge a lot less. I tell you example....the phone company charged me 180$ just because I cancelled my postpaid mobile bill to prepaid when I realised that is just a way they can take money from your account for no reason. I went to a skin clinic for Laser hair removal and then during consultation they offered me a lightening cream that they just sell as the sole company and said I have to use it because otherwise after laser I will have darkening of my skin so they charged me 200$ just for two creams..a sunscreen crean and a lightening cream ....I bought a book and and dvd for my child for 10$ and when I came home and watched the DVD it was just for 5 minutes and of no use...absolutely waste of money...and so on...