It has been awhile since I have seen a carrier officially release an OS 5.0 build for the 9530. This latest OS 188.8.131.529 was spotted by the team @BBRocks and comes from MTS Mobility. Hopefully it improves upon other builds.
Please confirm in the comments if this works for you
NOTE: Don’t forget to delete the vendor.xml file located in c:program files>common files>research in motion>apploader to install it on a different carriers device.