John,
>Error: Cannot implicitly convert type 'object' to 'decimal'
My syntax might not be right and I might be misunderstanding "casting" (I'm not a C# expert), but can you force a conversion to decimal in the return statement... something like this?
return (decimal)b.getbalance(custNumber);
Or perhaps store the return value to a var first that is forced to decimal, then return that?
decimal retvalue = (decimal)b.getbalance(custNumber);
return retvalue;