Perhaps it's because you RMA'ed at a bad time? Transferring over all those warranties and information over probably isn't easy and will slow them down.
Samsung RMA's with rexo have been real quick for me.
Seagate too, within a week I got a replacement drive after they received the faulty one.

Seagate on Tuesday reported financial results for the quarter ended December 30, 2011. Shipments of hard disk drives (HDDs) dropped only 3.1% in terms of units, but at the same time the Seagate's earnings increased by 18.5%, whereas the company's profitability rose whopping 375%.
This is off a per unit increase of $2.50 due to the flooding. We are being fleeced.
so, which is better to buy in this current crisis?
a 60GB SSD or 500GB HDD, both priced similarly.

The fat cats will always find a way to line their pockets, what really annoys me though is the normal working man or woman that defend these money grabbers.
I'm going down a completely different route for storage until this madness sorts itself out. My media server pool has RAID 0+1, so a stripe which is mirrored. Right now, instead of adding extra hard drives to increase the storage area on my arrays, I have actually deleted the second backup (RAID 1) mirror of my RAID 0+1 setup (I have two 2TB as RAID 0 plus another set same mirroring the first).
So instead of 3.7TB usuable with the same as a mirror, I have put all four in RAID5 giving me just over 5.5TB of storage space. So now I have more space with disc redundancy but no data redundancy.. so I just bought an LTO5 tape drive for £800 and that included 9 tapes. For almost the same money I could have bought 4 3TB drives.. but this way I just add more tapes when I need more storage. I don't know why I didn't think about this ages ago![]()

so, which is better to buy in this current crisis?
a 60GB SSD or 500GB HDD, both priced similarly.

Hinting about product availability at competitors and their pricing
[ source ]
I'd delete that message before you feel the wrath of Andrew Moore, OcUK don't allow any discussion of competitors even though you didn't name them.
