Ask her in writing to do repairs. If she refuses, you can have it repaired and deduct the cost from rent. http://www.statutes.legis.state.tx.us/
Read, read, read. There are several applicable statutes and it is confusing because you will need to go back or go forward to read associated statutes. There are several that describe fines and penalties against the landlord.

PROPERTY CODE
TITLE 8. LANDLORD AND TENANT
CHAPTER 92. RESIDENTIAL TENANCIES
SUBCHAPTER A. GENERAL PROVISIONS

Sec. 92.006. WAIVER OR EXPANSION OF DUTIES AND REMEDIES. (a) A landlord's duty or a tenant's remedy concerning security deposits, security devices, the landlord's disclosure of ownership and management, or utility cutoffs, as provided by Subchapter C, D, E, or G, respectively, may not be waived. A landlord's duty to install a smoke detector under Subchapter F may not be waived, nor may a tenant waive a remedy for the landlord's noninstallation or waive the tenant's limited right of installation and removal. The landlord's duty of inspection and repair of smoke detectors under Subchapter F may be waived only by written agreement.

(b) A landlord's duties and the tenant's remedies concerning security devices, the landlord's disclosure of ownership and management, or smoke detectors, as provided by Subchapter D, E, or F, respectively, may be enlarged only by specific written agreement.

(c) A landlord's duties and the tenant's remedies under Subchapter B, which covers conditions materially affecting the physical health or safety of the ordinary tenant, may not be waived except as provided in Subsections (d), (e), and (f) of this section.

(d) A landlord and a tenant may agree for the tenant to repair or remedy, at the landlord's expense, any condition covered by Subchapter B.

(e) A landlord and a tenant may agree for the tenant to repair or remedy, at the tenant's expense, any condition covered by Subchapter B if all of the following conditions are met:

(1) at the beginning of the lease term the landlord owns only one rental dwelling;

(2) at the beginning of the lease term the dwelling is free from any condition which would materially affect the physical health or safety of an ordinary tenant;

(3) at the beginning of the lease term the landlord has no reason to believe that any condition described in Subdivision (2) of this subsection is likely to occur or recur during the tenant's lease term or during a renewal or extension; and

(4)(A) the lease is in writing;

(B) the agreement for repairs by the tenant is either underlined or printed in boldface in the lease or in a separate written addendum;

(C) the agreement is specific and clear; and

(D) the agreement is made knowingly, voluntarily, and for consideration.

(f) A landlord and tenant may agree that, except for those conditions caused by the negligence of the landlord, the tenant has the duty to pay for repair of the following conditions that may occur during the lease term or a renewal or extension:

(1) damage from wastewater stoppages caused by foreign or improper objects in lines that exclusively serve the tenant's dwelling;

(2) damage to doors, windows, or screens; and

(3) damage from windows or doors left open.

This subsection shall not affect the landlord's duty under Subchapter B to repair or remedy, at the landlord's expense, wastewater stoppages or backups caused by deterioration, breakage, roots, ground conditions, faulty construction, or malfunctioning equipment. A landlord and tenant may agree to the provisions of this subsection only if the agreement meets the requirements of Subdivision (4) of Subsection (e) of this section.

(g) A tenant's right to vacate a dwelling and avoid liability under Section 92.016 or 92.017 may not be waived by a tenant or a landlord, except as provided by those sections.