First of all, you can not update to 12.5.5.1086 (=SP4) via SIM since the version 12.5.5.1086 (=SP4) is the version of pcAnywhere Box product which is not dependent on SIM.
As you said you are on NS 7.0.8800 with pcAnywhere showing version 12.5.539, please upgrade to the latest SIM version and select "Symantec pcAnywhere Solultion 12.6.7 (Version 12.6.8096)" from the product list to upgrade to the more secure version of pcA solution.