Actually I don't have this problem. Perhaps it is only the SAP SSO 2.0 which works with the RFC calls of the TMSSUP* destinations, but I don't believe that. I am pretty sure there is something wrong in the SNC setup and TMS config distribution if SNC is not working.
SAP support also works for me. Delays are not enough to complain about if dealt with tactfully. Mostly things are very fast but at time a co-ordination for features to make them more easily implementable are needed. Sometimes you even need to wait for a major release change if there are compatibility concerns and both kernel and application coding corrections are needed.
Cheers,
Julius