Possible abuse of power of attorney

[Pete525d]

Hi recently my nan past way and she was ill for over a year my aunt got power of attorney and she along with her son became primary careers for my nan how ever it seems that my nans pension and other benefits and a large injury claim money has been spent and we have no idea where the money has gone we believe that my aunt and her son were taking money out of her account also she became executor of her will and had it changed so my aunt and her son got included and some other family members got taken out any advice would be appreciated