What you can do in Seremban is for food hunting.

Morning (7-11AM)
GMap - 2.730603,101.936719
You can visit to Pasar besar at town center, go to second floor, there are a lot of nice food over there.
牛腩粉 - 新儒记
鱿鱼米粉 - There are 2 shops selling it, both nice too.
云吞面 - 1) 12 o'clock from 新儒记, 2) 8 o'clock from 滔记 hakka mee
客家面 - 滔记 Only one shop selling it, find the shop with a lot people standing waiting for tabao.

Lunch (from 12PM - until finish)
(not sure Sunday open or not)
GMap - 2.728695,101.936955
Famous 潮州粥, must try their 咸菜

Lunch (from 12PM - until finish)
GMap - 2.729124,101.939015
expensive Chicken rice a.k.a we called in 黄金鸡饭

Dessert - Cendol + Rojak
Haji Shariff Cendol
GMap - 2.726635, 101.940081

Seremban Siew Pao
There are lots of brand currently in Seremban, one of my favarite is 华师傅芙蓉烧包
GMap - 2.728347,101.938785 <-- don't know this branch still open or not.
GMap - 2.697595,101.936945 <-- i always buy it from this branch

Dinner.... no recommendation, the so called 芙蓉烧螃蟹 is not famous within the local people