You can use both words together, but it means something different from what I think you're trying to say. しか+Verbない is used to express that the preceding thing is the only thing that is true.
Thus, you should understand
1万以下しか貰わなかった
as meaning that the only thing that is true is
1万以下を貰った
B didn't get a bonus of 1万 and certainly not over 1万. The only kind of bonus B got is a bonus that is under 1万.
If you want to express that a bonus of under 1万 is less than expected (i.e. you expected a bonus of 15万 but instead got a bonus of 1万), then you would want to say something like this:
ボーナスといっても、1万以下は思ったよりも少なすぎてがっかりした
ボーナスといっても、1万以下は思ったより少ない金額だった。