T-Mobile has engaged in a marketing campaign called “Make Xfinity Your Ex” that aims to convince Comcast Xfinity customers to switch to T-Mobile’s fixed wireless access (FWA) 5G Home and Business Internet service.   As part of the campaign, a T-Mobile billboard truck has been driving circles around Comcast’s headquarters in Philadelphia for 25 hours, playing a video that highlights Comcast’s price hikes over the years.    In addition to the billboard truck, T-Mobile is offering its FWA 5G service for $25 per month, not including taxes and fees, with a qualifying voice line for a limited time, and is giving Comcast Xfinity customers up to $750 to break their contracts.   The campaign is a direct attack on Comcast, which is set to raise prices on its TV and internet services, with an average rate increase of 3.8% for customers nationwide starting December 20. This follows a rate hike…