I had a chat a while ago with some very chatty, helpful CS agents at exec club, and mentioned that I might be 5-10tp short of silver and asked if they would boost me to it anyway. They said the first time you make it, absolutely not, but if you had been silver/gold regularly before that they could. So rather than asking for an extension (what from what I understand, could be retroactive anyway) Id try asking them to just renew you anyway as goodwill, without the extension, and then go the extension route if that fails.