I had a 5-night stay back in late July in Alaska that should have cost 180000 points. Still absolutely no points deducted over 5 months later, even after I mentioned it to BW customer service once (a couple months after the stay).
Meanwhile, back in late November, I had a free nigh cert stay for one night in the California desert and the hotel mistakenly took out 20000 points instead, and promised to return it (after I checked in with the free night cert) but those points are still not there, and I keep forgetting to call them in the narrow window of time certain days of the week when the right person is there at the hotel.
Anyway, in your case, if it won't take that long to build up enough points to cover that, stop staying on points at that hotel, and wait until you've built up enough to cover all your redemptions, and then contact them.