T-Mobile certainly knows a good opportunity when it sees it. The “Uncarrier” on Monday unleashed a public relations barrage against its rivals that urged wireless customers to sign a Change.org petition telling Verizon and ATT to dump overage fees on mobile data plans. “Traditional wireless plans start with a low monthly fee for a fixed amount of domestic minutes, texts or data,” T-Mobile writes in its petition. “Once consumers go over those limits — even by a little — they’re hit with dramatically higher rates and extreme penalties. These plans seem purpose-built to drive customers over that invisible line into massive overage charges. “ T-Mobile first started targeting rivals’ use of overage fees last week when it unveiled its new