POA Management Company not responding to homeowners

The management company works at the board's direction, so the board is the group you should be talking to and demanding answers. Have you asked for and reviewed board meeting minutes where these expenses were discussed? What were the invoices for - what seems large to you might be common for vendors in your area. If it's a major repair, it may be the cost went up after the vendor started work and found other problems that couldn't be identified because things hadn't been opened up (e.g. piping for the clubhouse). You should also know whether the board obtained more than one bid for the work to ensure they were getting a fair price for the work.

Go to your next board meeting with your neighbors and demand answers - if you're ignored or get a lot of doubletalk (or no answers at all), check your documents to see what they say about calling a special homeowner's meeting. It might be time to consider if one or several board members need to be recalled. Of course, that'll also mean you'll need people to step up and volunteer to serve if the recall is sucessful (you may need to be one of them).

Large amounts for what?