Ask an Property Solicitor. Get an Answer ASAP.
The management company cannot just do this as they please. If they wish to increase charges as such, they must refer to this in the annual general meeting with the residents and here, they must provide the residents with a chance to dispute the new proposed arrangement. In addition to this, they must show that they have valued the new amount correctly and also show proof of this (by way of a survey or valuation report).
Re the service charge accounts, I would request a copy of the last 3 years accounts (at the minimum) to view what you have been paying and to also review what for. I would threaten them with the following courses of action;
Leasehold tribunal (a threat is normally enough to make these companies back off) -https://www.gov.uk/leasehold-property/leasehold-disputes
Breach of the Service Charge residential management code 3rd Edition - https://www.rics.org/globalassets/rics-website/media/upholding-professional-standards/sector-standards/real-estate/service-charge-residential-management-code-3rd-edition-rics.pdf
I hope this helps and please do leave positive feedback. If you have any further questions, please do let me know.
No problem Katie, always happy to help.
Please let me know if I can assist with anything else.
Costs can generally accrue but from my knowledge, it isn't cheap! You can raise a formal complaint with the property redress scheme and also the property ombudsmen - further information can be found herehttps://www.lease-advice.org/article/property-management-redress-schemes-what-leaseholders-need-to-know/
No problem :)