Vacuum cleaner. hi.this is 10 yrs old and not overly worked.bags are changed regularly and the

Question

hi.this is 10 yrs old and not overly worked.bags are changed regularly and the micro filter has been changed at least three times over ten years.it goes well for about 2o minutes then loses power with not much "suck"after that.sometimes shutting down completely,because of overheating i presume,or just carries on at a much lower'"suck".have tied shaking bag inside but no luck.any suggestions out there or can you tell me the agents support office for new zealand[auckland].many thanks.