I must clarify what has been posted "that without a certificate no charges are due"
If as in #11 a interim payment is made, the relationship between the end of period certification (under the lease) varies between leases.
In general terms, as leases are infinitely variable;
-It is therefore conceivable, and relatively common, that the interims stand alone in the calculation of the estimated charges whehter or not a certificate in produced. The only remedy in that case is not simply the LVT, but the County Court to order the landlord meet the terms of the contract-the lease- and certify. While the LVT might determine what is due for a period the landlord can still insist on his interims and the court would be require him to reconcile them as the lease dictates.
-In the case where any surplus is rolled into reserves, the interims would still be due as demanded, unless the the LH challenged them ( and the RF) as being fair and reasonable at the LVT.
-It is only where the service charge is expressed as calculated as a final charge, in arrear, less any on account amount, that the LVT might then determine"the" service charge.
Based on the information posted, I offer my thoughts.Any action you then take is your liability. While commending individual effort, there is no substitute for a thorough review of documents and facts by paid for professional advisers