how to leave a good customer service review?

Never in all my existence on this planet have i ever been so frustrated with an internet provider. i will never ever even speak to anyone at tmobile again. i went to a local tmobile to try and get a wifi hotspot and they told me it was buy one get one free. They did not tell me that it would not be free and i would end up having to pay over 400 dollars to them(200 each). they also lied to me and told me they had unlimited data when they only have 50gb of data on each. I now have to pay over 400 dollars which i cant even pay because their mobile app is so so im probably gonna be charged late fees. But yeah if youre looking into tmobile just make sure you know what youre getting because they will lie to you just to get their money. TMOBILE IS ABSOLUELY HORRIBLE