-25% by using Shopee Coins, capped at 3000 coins / 24 hours.
Coins are mined FOC from Shopee Games and Shopee Live.
Some Android users may buy Coins at discount.

IOS users won't find it if I am not wrong. At Shopee Prizes -> COINS SALE.
1550 coins were being offered at discounted price (RM13 if I am not wrong), sold out at this moment.

For Unifi, you can always pay any amount >RM30 at Shopee, >RM10 at Lazada, advance payment is also allowed. My Unifi, water, electricity (except TNB) accounts are with negative outstanding balance.

Frankly speaking, if you don't accumulate a lot of Shopee Coins (from shopping at Shopee, Shopee Prizes, Shopee Live, Maybank-Shopee Card etc). You won't save a lot if you buy coins. Lazada is a better choice, you can use the Lazada vouchers from Voucher Club (invited user only), LazLive etc. eg I managed to grab some RM5 (minimum spend RM66, valid on 16/6-18/6), I will pay to my Unifi / Sarawak Energy account RM66 (advance payment), using PB VS/QM/Amex to pay RM61 (5%-6% rebate from credit cards). 

Yes I used it in May. My RM10 Voucher Club just ended, don't know when I will get invited again, so I can't reconfirm at this moment.
Worth to try out, only RM10.

(60-10 vouchers restricted to Lazada Wallet, you will see -RM10 only if you choose Lazada Wallet)