Begin with the diagnosis
Ask what was found, what work is proposed and whether any other issue needs attention. A symptom alone is not enough to decide that replacement is necessary.
Compare complete costs
Understand parts and labour for a repair and any installation requirements for a replacement. The purchase price of a new heater is only part of the comparison.
Check the requirements
A different model or power rating may require a professional assessment of electrical and water services. Do not assume that a similar-sized heater can use the same installation.
Confirm terms
Ask what warranty applies to the proposed work or parts and keep the information provided before agreeing to the next step.