Dear members

I have power operated rear tailgate, which was doing excellent till 1 week ago , when out of sudden started to have an issue:

the tailgate opens normally till it reaches the maximum, and then it fails to stay open; closes again silently, without hearing the motor sound,

could anyone advice what is the problem here, I called the company and on phone they said ( its is a normal issue to this model , and needs to install the whole new set of hydrolic system !!!

can anybody advice regarding this , or anyone with same issue ?