Legal Issues Involved:

1. Restraint of Trade: The agreement between Bature Company Limited and its distributors, as well as the subsequent agreements between the distributors and their customers, may constitute a restraint of trade. Such agreements are typically void under common law unless they are reasonable and justified in the interest of the parties involved and the public. Bature may argue that the restriction is reasonable to maintain market stability, but Chinedu Enterprises could challenge this as an undue restraint on their ability to freely trade.
2. Breach of Contract: Chinedu Enterprises signed an undertaking not to sell the air conditioners above ₦200,000 but breached this agreement by selling them at ₦250,000. Bature Company Limited can sue Chinedu Enterprises for breach of contract since the agreement was specific on the resale price. Damages may be awarded to Bature for any financial losses resulting from the breach.
3. Enforceability of the Agreement: One of the key legal issues here is whether the price control clause in the agreement is enforceable. Courts typically view such clauses with caution, as they may distort market competition. Bature Company Limited would need to show that this clause is necessary for maintaining market fairness and not merely for restraining competition.
4. Remedies Available to Bature Company: Bature Company Limited can seek legal remedies such as damages for breach of contract or an injunction to prevent Chinedu Enterprises from selling at a higher price in the future. They may also claim any profits Chinedu made above the ₦200,000 resale price.
5. Third-party Rights: Although Chinedu Enterprises was not a direct party to the original contract between Bature and its distributor, the undertaking signed by Chinedu means that Bature has a legal right to enforce the terms of that agreement against Chinedu Enterprises.

Conclusion:
Bature Company Limited has a strong case for breach of contract against Chinedu Enterprises. However, the restraint of trade aspect may complicate the case, and Bature should seek legal remedies that emphasize the necessity and reasonableness of the price control in their market strategy.