You instructed a quotation for a proposed instruction.
Having received it, you are not responding to it within the contractual timescales of clause 62.3. Consequently - and this would presumably be reinforced by the detail in the quotation - as a (Sub)contractor, I would argue that any acceptance is out of time and not valid. (Note : in NEC4, the issue of proposed instructions has been significantly tidied up in terms of reducing contractual loose ends - see clause 65)
So you start again, either
- instructing the works as a change to the Works with the quotation to follow or
- instruct a revised quotation for a proposed instruction.