Why is the legal process of buying/remortgaging so bad in the UK?

We’re having a nightmare with the remortgage right now. We stupidly decided to switch lenders as they were offering a lower mortgage rate, but the solicitors keep adding more and more additional costs on top of the quote they initially quoted (so far twice as much as the initial quote). We’re now stuck in a position where financially this is going to be a big hit on us, having to pay the solicitor and the mortgage advisor who ended up giving us shite advice. In hindsight, sticking with our current lender would’ve been the way to go, despite being a higher interest rate. In future, we’ll do everything we can to avoid dealing with solicitors as they’re all a bunch of shysters. It’s our first remortgage so we’re viewing it as a learning curve, but solicitors really should be heavily regulated to prevent them screwing over the customer.