In order to express the notion of having someone else do something for you, use a form of have + the main verb:

–I'm having my mail forwarded.
(Someone else is forwarding it for you.)

–I had my house painted.
(Someone painted it for you.)

Let in a causative sense means to permit:

–Please let me help you.
–Don't let them leave!

Do not use an infinitive after let.

Examples of To Have and Let (Causative)

• We'll let our credit office work out the details.
• I'm having all my mail forwarded to my attorney's office while I'm out of town.