They obviously have that in place for a reason and are not privy to give you an explanation of why they have it in place. The techs you have dealt with probably have no clue why that policy was put there, but it's there and there is no way to get around it despite your repeated requests.
Also, VPS plans are cheaper than cell phone plans now. It's like going to 7-11 for a soda compared to a grocery store- the grocery store may be cheaper but 7-11, more often than not, is more convenient. If you are in the business of making money off your sites, consider getting one so you don't have to face issues which you are currently experiencing. My 2 cents.