DWG Plans Editing

I need professional assistance to edit DWG plans. The required amendments include:

Changing dimensions:
- Overall building dimensions
- Room dimensions

Modifying existing elements:
- Doors and windows

Ideal skills and experience:
- Proficiency in AutoCAD or similar software
- Experience with architectural plans
- Attention to detail and accuracy
- Ability to work within specified dimensions and modify elements as required

Please provide samples of previous work and estimated completion time.

I want to amend existing architect plans by:
- Extending to the back a further 1.3m
- Increasing the ceiling height of the back extension by 30cm
- Making small changes to window placement