Seems a bit low to me and sounds like you received credit for only one of the rooms. If I had to guess, they probably calculate points based on the pre-VAT room rate (& any other fees/taxes in there). Then with a generous GBP to USD exchange rate in MR's favour, RI @ 5 points = $1USD could partially explain the low points earn. Would be worth a follow up about that second room - suspect you'll have to write or call in.

Just my thoughts though!