Hi,
I can Recommend some of the colleges that provide Diploma in Fashion Design with a course period of 1 to 2 years:
1. NIFT Bengaluru
2. PEARL Academy
3. Madras Institute of Fashion Technology
4. Lovely Professional University Punjab
5. INIFD-Vashi.
All the above institutes are among the reputed Design Institutes that offer Fashion Design Course.
As, you have not mentioned the city you are living in, you must check the above-mentioned institute's websites to find if they offer the required Diploma in Fashion Designing you are looking for in the city you reside in.