I'm in shock!! Just called Cap1 (backdoor) and got a $300 (whoopee!) CLI on my Platinum - that brings me to the grand limit of $1050. I hadn't bothered calling before, because I was under the impression they never ever increase CLs on Platinums after that measly 3-month increase for being good with your credit.
I actually wanted to find out if any kind of upgrade to a less dull card (no hassles cash, for example) might be possible, but got the 'not at this time' response - there's obviously certain offers available that they can give, and nothing beyond that.
I have to say the CSR I spoke to was absolutely great - infinitely better than any Cap1 CSR I've ever encountered! She mentioned that they are 'proactively' trying to make their cards more desirable to their customers and give them the features that they actually want. She was very very apologetic that they didn't have any upgrades to rewards cards 'available' for me, but seemed to think that it couldn't hurt to keep checking back as I am doing 'all the right things' and using my card in the way that they 'prefer' their customers to use them (and there was me thinking they preferred the ones who run up huge balances and pay a fortune in interest every month)... maybe the evil machine that controls who gets what with Cap1 will ensure that I never get a decent card off them, but she was very lovely and helpful nonetheless!