Depends a lot on the terms of the lease. But most leases say that you're not really allowed to do your own repairs. The landlord can do them to his own satisfaction.
That being said, the repairs still have to be reasonable. You can certainly contest the amount of his charges, but that would probably require filing suit in small claims.
This answer does not constitute legal advice and does not establish an attorney-client relationship.
First and foremost, you need to review your lease for any language that addresses this situation. If the lease is silent, then the landlord does have the right to make reasonable repairs and bill you for the same.
If you disagree with the "reasonableness" of these repairs, you can withhold payment. However, if you withhold payment, you are opening yourself up to a potential lawsuit which could result in an eviction.
I suggest you contact a local Landlord Tenant Lawyer to review this matter in more detail before taking such actions.
If you liked this answer, please rate it "HELPFUL" or "BEST". You can contact Michael I. Werner, Esq. for further detailed answers at 412-904-5305. **DISCLAIMER** Michael I. Werner, Esq. is licensed to practice law in the Commonwealth of Pennsylvania. His practice focuses on Pennsylvania Landlord-Tenant Law (representing both Landlords and Tenants), Pennsylvania Estate Planning, Pennsylvania Real Estate, Allegheny County Property Assessment Appeals, Allegheny County Real Estate Tax Appeals, and General Business Matters. This answer is based on general legal principles and is not intended for the purpose of providing specific legal advice or opinions. This answer does not constitute the establishment of an attorney-client relationship. It is always recommended that you consult with an attorney prior to taking legal actions on your own.