Contract not gone through :S

My mother accepted a contract for 250mb for £43 however this has not gone through and we have a bill for £66.73 which is stupidly high. We went back to live chat and spoke to someone at virgin media who told us everything was okay and we've have to wait for the direct debit however this is not the case and £66.73 than what we could pick online so this is obviously taking the mick.