“ 19. The contention that the appellant by its conduct has waived its right to object to the appointment of the learned Arbitrator is also without merit. The question whether a party can, by its conduct, waive its right under Section 12(5) of the A&C Act is no longer res integra. The Supreme Court in the case of Bharat Broadband Network Limited v. United Telecoms Limited: (2019) 5 SCC 755 had explained that any waiver under Section 12(5) of the A&C Act would be valid only if it is by an express agreement in writing. There is no scope for imputing any implied waiver of the rights under Section 12(5) of the A&C Act by "20. This then brings us to the applicability of the proviso to Section 12(5) on the facts of this case. Unlike Section 4 of the Act which deals with deemed waiver of the right to object by conduct, the proviso to Section 12(5) will only apply if subsequent to disputes having arisen between the parties, the parties waive the applicability of sub-section (5) of Section 12 by an express agreement in writing. For this reason, the argument based on the analogy of Section 7 of the Act must also be rejected. Section 7 deals with arbitration agreements that must be in writing, and then explains that such agreements may be contained in documents which provide a record of such agreements. On the other hand, Section 12(5) refers to an "express agreement in writing". The expression "express agreement In writing" refers to an agreement made in words as opposed to an agreement which is to be inferred by conduct. Here, Section 9 of the Contract Act, 1872 becomes important. It states:
