It would depend on two things:
- if they are a public sector client or a utility then they are subject to the 'The Public Contracts Regulations 2015' and almost certainly should have run a separate competition for this supplier. Practically though, all you can really do is threaten to tell the internal compliance committee and alert other suppliers who would have liked to have competed and let them take up the challenge. Realistically, this might stop them doing it again, but does not help you.
- how tightly the spec is defined. If another supplier can meet them, then there is no contractual reason not to use the other Subcontractor. If they then insist on using the one who supplied the drawing, then the PM needs to instruct a change to the Works Information (under NEC3) or Scope (NEC4) which is a compensation event. The additional cost + Fee from doing this is the value and they may be some delay and resulting cost too!
- if they are a public sector client or a utility then they are subject to the 'The Public Contracts Regulations 2015' and almost certainly should have run a separate competition for this supplier. Practically though, all you can really do is threaten to tell the internal compliance committee and alert other suppliers who would have liked to have competed and let them take up the challenge. Realistically, this might stop them doing it again, but does not help you.
- how tightly the spec is defined. If another supplier can meet them, then there is no contractual reason not to use the other Subcontractor. If they then insist on using the one who supplied the drawing, then the PM needs to instruct a change to the Works Information (under NEC3) or Scope (NEC4) which is a compensation event. The additional cost + Fee from doing this is the value and they may be some delay and resulting cost too!