Looking for help with customisation of the default UmbracoMembershipProvider.

Basically trying to overide the default ValidateUser method so that locked member accounts can be automatically unlocked after a predefined time limit.

However it seems that the value for LastLockoutDate increments on each validation attempt. Despite the fact that the Unlock is called before the base ValidateUser method.

Below is the code for the Validate user overide -

public override bool ValidateUser(string username, string password)
        {

            MembershipUser mui = this.GetUser(username, false);

            if (mui.IsLockedOut && !AutoUnlockUser(mui))
            {
                return false;
            }

            bool retval = base.ValidateUser(username, password);
          
            if (retval == false)
            {
               return false;
            }
            else
                return retval;  //first login was successful
            }
      
        }

And code for AutoUnlockUser -

protected virtual bool AutoUnlockUser(MembershipUser mui)
        {
            DateTime now = DateTime.UtcNow;

            if (EnableAutoUnlock && (mui != null) && (mui.IsLockedOut))
            {
               
                // if enough time has passed since the last lockout date, unlock the user
              
                    if (mui.LastLockoutDate.ToUniversalTime().AddMinutes(AutoUnlockMinutes) <= now)
                    {
                        mui.UnlockUser();
                       Member m = Member.GetMemberFromLoginName(mui.UserName);
                       m.getProperty("locked").Value = "0";
                       m.getProperty("pwFails").Value = "0";
                       return true;
                    }
                    else
                    {
                        return false;
                    }             

            }          
            return false;
        }