I know others have already mentioned this, but there are terms and conditions on accounts which specify how the account can be used ... they do mean that if you try to use a personal account for business purposes, they could close it. Unfortunately, the same applies to all banks, so moving wouldn't really help you much.
As much as I dislike banks as much as the next guy, at the end of the day, we all used to pay fees to have bank accounts, it was only in the 80s that they started offering "Free" accounts, and then compensating for it by increasing the charges for overdrafts and other things. They're not legally obliged to offer us a free service. And I bet, if you've got any commercial work, you charge them more than you do your residential customers ... just because they're a business ... it's no different to what the bank's doing, it's just how they run their business, and like your customers, if they don't want to pay the price, you don't give them the service!
Most banks do offer some kind of "Free" business account ... ie. there's no monthly fee, and certain transactions are free although you have to pay for others. In most cases, paying in cash and cheques will cost you a fee, but if you can train your customers to pay you by standing order or online bank transfer, they are all free! And it will actually make your book-keeping easier because you're keeping your earnings and business expenses separate from any other money coming in and out of your account. You just pay yourself by taking "drawings" out of the account to your personal one once a week, and then pay all your personal and home bills out of the personal account.