mypengo mobile review: con text messages

On checking my mobile contract bill I found that I had been charged for 4 premium texts received on May 28th at 13.45 of £1.25each text all at the same time sent and one on May 29th at 21.01 making my bill an extra £6.25 plus £1.50vat I never actually reveived these texts but three.co.uk said that they were just sent to my mobile and I would have to claim refund from the firm. I only started my new contract on 13th May 2013 only 2 members of my family communicate on this mobile, no other company or anybody else has my number except of course three.co.uk. How did this company get my number? their number is 85150. As an oap I only have my mobile for emergencies only as I use my landline phone for all calls. Mypengo mobile dosen't seem to be available to complain to, their number is [protected]. I am writing to three.co.uk to try and get them to stop all these types of texts and calls to my mobile (if I can) what else can I do as I cannot afford to pay out money unnecessary thank you