Have you had it on diagnostics to find out what fault codes are logged regards why it went into failsafe mode?
The TB shift motor is expensive and throwing one at it and it turns out not to be that is false economy.....
The GM5 box on the Td6 is a major weak point, and are known to lunch themselves with grave regularity, the chief cause is the valve block that wears out due to soft materials.
The first thing is to get it on diagnostics as it may point you in a direction of what to check next....guess work is fool-hardy.
Thanks a lot for the prompt reply, I am just looking for my options for diagnostics checks done near to my place as I am in East London and trying to find a reliable garage for the same. Will get this done and update the post accordingly but if anything worse happen, then will come back soon here.
fingers crossed!!!