1. What after service can you offer?
你们能提供什么样的售后服务？
还能这样说：
How can you offer the after service?
What about the after service?
应用解析：
active service 实际战斗，实战；
at one's service 为某人效劳；随时提供服务；
customer service 客户服务；
service quality 服务质量
2. It can be refunded if there is something wrong with it.
如果有问题的话，可以拿来退货。
还能这样说：
If something goes wrong, it can be refunded.
You can return it if there is something wrong.
应用解析：
tax refund management 退税管理；
refund the balance 补偿差额；
charges refund 运费退款；
refund sth. to sb. 退还（所收的钱），偿付（花去的费用）
3. Can I have a refund?
我能不能有退款？
还能这样说：
Can I have my money back?
Can I get a refund for it?
4. We offer maintenance for the goods.
我们提供保养维修。
还能这样说：
We provide the customer maintenance service.
We are responsible for the maintenance.
应用解析：
breakdown maintenance 故障维修，停工检修；
annual maintenance 年度保养；
maintenance order 赡养令，抚养令；
effective maintenance 有效维护管理