No limit increase, but please buy a phone

I am receiving sms's from them to increase my limit which I want to do. Tried in store on my phone and even over the phone to the office. No luck. But they keep on sending the sms and even trying to sell me cellphones. The last time I asked them why I can't increase the limit and was told apparently my account was flagged for *****. The account is barely a year old and I didn't flag it for *****. They just ignore me if I want to increase the limit but is good enough for a new cellphone