Here are some suggestions and possibilities.
1. If there is anything else you need, please, let me know.
2. If I can be of any further assistance, please, let me know.
3. If there is anything else I can do for you, please, don’t hesitate to let me know.
4. Please, feel free to let me know if you require any further information.
5. If I can be of any further help, please, call or send an email.
6. If I may be of any further assistance, please, let me know.
7. If you require additional information, please, let me know.
8. If you have any additional questions or require further clarification, please, do not hesitate to call me or send me an email.
9. Please, let me know if you require additional information or further clarification regarding this matter.
10. If you have any other questions or would like me to clarify anything else, please, let me know. I am always glad to help in any way I can.
These statements are more casual and sound less formal.
1. Let me know if you need anything else.
2. If you need any other information, just let me know.
3. If you have any questions, just let know.
4. If I can do anything else for you, just let me know.
5. Call or send an email anytime if you need anything else.
6. If there’s anything else you need, just let me know.
