That is horrible, I would ask for manager right there. First 4PM is not acceptable, second, attitude is horrible. If they do not have enough people to clean then hire more or do not let everyone to have late check out.
Staying at BLT as
DVC members (check-in at 4pm), our room was not ready until a little after 5pm. We had been there since 11am. With two kids under the age of 4 who hadn't napped, we were all a little cranky!

Of course,
our choice to show up at 11am!!
I went directly to the front desk (as I always do if there are any issues), and was told that the check-in policy (in practice) is really more like
"begins at 4pm".

At that point I asked for management. I stated my displeasure with what I referred to as a "unique" rule based on my traveling/hotel experience (including working in the hotel biz for a stretch).
I didn't seek any "compensation" of any kind, and just suggested (for what it was worth), that if this really was the case, Disney should revise how it communicates with guests re: what "check-in time" really means. Management was VERY nice, very apologetic, tried to find a room in our category to put us in immediately, etc. Once we were in a room, the manager called to see if we were all settled.
For us, though we were a little cranky for a bit, this was
no big deal, really. Neither was the phone that didn't work in the room, or the TV whose cable was mysteriously disconnected from the wall (took us a while to figure that was the issue - those flat screens are a little odd!). Things were fixed in pretty short order, and we went about our business.
Honestly, I forgot all about ALL of this until reading this thread!

Gotta' love

!! The magic of Disney, even if a bit delayed, wipes out all the small stuff for us!