Would depend on all relevant information being supplied would this one Dannyboy i.e Materials used, partition height, length, Track & Stud used or timber, are metal studs (if installed) ‘boxed' or not, stud centers, boarding spec...
If the wall is deflecting, that sounds like a lack of adequate sized or un-boxed studs?
I would need more information on that problem but, if the wall has been installed as per the Architects specification i.e as per the drawings then He's responsible, it's not up to you to to determine what the manufacturer has told the Architect - did you have a Site Inspector / Clerk of Works on site?
Regards
MVM