By Lars Mucklejohn Vanquis Banking Group has revealed that it is involved in legal proceedings against a claims management company. Back in March, shares in the lender fell off a cliff when it told the market it would have to book higher provisions due to mounting legal costs. The Bradford-based bank’s profit warning was triggered by administration costs tied to a surge in third-party claims, mainly from a single complaints management company, relating to Vanquis’ credit card business. Shares in the specialist lender cratered as much as 45 per cent after the warning, and later that month, it r…