Sharkfrenzy again... @ PHX on Wed, outbound on two separate reservations... PHX-IAH, then IAH-GRU. Both UA metal, both 016-plated. OLCI worked fine. I printed BPs for both sectors successfully at kiosk... then asked the agent to tag bag to GRU instead of PHX. Yes, I know about interline rules on non-Star carriers etc. The agents wanted to assist me avoiding exiting and retrieving bags at IAH for recheck.... I appreciate their efforts. Buuut... meltdown...30 mins passed while they attempted in numerous ways to do so. Agent called supe, she couldn't figure it out either. Meantime, the agents were besieged by pax needing to pay bag fees and other ancillary charges, and handle the usual kiosk inability to check in on numerous modified itins.... none of which could be processed thanks to the payment system meltdown - the same one UA has been featuring on the homepage since yesterday. At least the agent comped the bag fee for the guy in line behind me... Finally the agent called IAH and was able to resolve this. I asked what the deal was, since it impeded everyone s experience with UA at that station. Apparently Aero doesn't recognize R as a valid booking class - ironic indeed since it's UA themselves who defined these booking classes - and either my EUA'd sector to IAH or my GPU'd sector to GRU - both showing R - confiunded Aero and caused a mismatch. Apparently bag tags can't be generated with any mismatch...hence the cluster. Now, the reasons why this became other people's problem and NOT JUST MINE: classic UA outsourcing @ PHX meant that two of the agents were contract, slinging bags after tagging but not able to access any UA system to resolve such problems. They couldn't deal with this and had to call UA supe in from other tasks. When these problems happen, which is inevitable, the lack of capacity causes a checkin meltdown. If you don't think this means anything then you obviously were not privy to the commentaries of the FIVE pax held up behind me, all of whom were MP Gold and above. Thread for attention of Oscar and Aaron. Can't you guys fix these things? We all want it to work better than it does.