Elderbridge mortgage /First Plus

[Mashka]

I took out a 2nd mortgage loan with first plus over 10 years ago. (Now with Elderbridge) I was advised by the loan broker at the time to apply for the loan in joint names with my wife as it would be more likely to be successful. My wife was unemployed with no income at the time and the main mortgage was and still is in my sole name. I wrote to Elderbridge recently as we wish to take her name off the loan agreement. They have refused as they say my income alone is not enough. The outstanding amount is around 50k and never been any arrears. Has anyone any advice on my next step to remove my wife's name?