If it's NEC3 ECS and assuming you're talking about Options C, D or E, then the Defined Cost of Subsubcontractors is at clause 11.2(23), not in the Schedule of Cost Components (SoCC).
If it's NEC4 where Subsubcontractors were moved into the SoCC, and the Client has deleted this by Z clause, then unless they've included it elsewhere it means you cannot be reimbursed the cost of Subsubcontractors which seems unusual.
I suggest you check all your Z clauses and make sure you understand how the contract operates, if it turns out Subsubcontractors have been completely removed from Defined Cost and you are going to give work to a Subsubcontractor you may need a deed of variation to the contract to sort the problem out. If this is the case I would start by notifying an ambiguity or inconsistency under the clause 17.1.
If it's NEC4 where Subsubcontractors were moved into the SoCC, and the Client has deleted this by Z clause, then unless they've included it elsewhere it means you cannot be reimbursed the cost of Subsubcontractors which seems unusual.
I suggest you check all your Z clauses and make sure you understand how the contract operates, if it turns out Subsubcontractors have been completely removed from Defined Cost and you are going to give work to a Subsubcontractor you may need a deed of variation to the contract to sort the problem out. If this is the case I would start by notifying an ambiguity or inconsistency under the clause 17.1.