When you use credit card, whether is it a one off payment or instalment plan, there is a fee to be paid. It is either absorbed fully or partially by Retailer/Merchant. Interest is altogether a different thing to this fee. This fee can range from 3-5% normally.
Why do Retailer/Merchant want to absorb such fees? Nets only support up to $3k-$5k daily limits. If somebody wants to buy something that costs more, credit card that can allow one to buy more than the Nets daily limits (e.g. $20k). Interest free instalment plan on credit card is prearrange between the Retailer/Merchant and the Card Issuer (DBS/UOB/OCBC/Citibank etc). It is easier to buy on credit/instalment than paying up front lumpsum. This helps to drive up sales for the Retailer/Merchant.
The 3% is the admin fee. The credit card instalment plan is not much different from a personal loan, where there is an admin fee and a separate interest rate, in this case 0% for interest free instalment. Some Retailer/Merchant prefer to use cash (no fee to pay) or Nets (much lower fees, less than 1% if I am not wrong).
Some companies will pre-arrange with the card issuer. An example below is the OCBC 0% interest free linkup with the various Retailers/Merchants
https://www.ocbc.com/personal-banking/cards/card-services-0-percent-installment-plan.html
Normally, the agreement between the Retailer/Merchant with the card issuer is such that Retailer/Merchant will not impose any fee on the consumers. E.g. an $1800 item pay by cash will be $300 monthly instalment over 6 months without interest. The Retailer/Merchant may have negotiate to pay only 2% fees instead of 3-5%, but we would never know. It is like the $0.25 EZlink Auto-reload fee. For Retailer/Merchant, 2% more costs but the sales may drive up by 20%.
I once tried to buy something from TK Foto, a photography equipment retailer. I remember they charge 3% or 4% if I pay by credit card or credit card instalment plan (which is interest free). They do not absorb the fees.
I explained in above, it is interest free credit card instalment. If you see the link below, it shows that iStudio is one of the participating Retailers/Merchants. It did not say that there is a fee or no fee. It is also the same for OCBC where no where it mentions there will be a fee or no fee.
What is likely to happen is the iStudio pre-arrange with card issuers for interest free instalment, but iStudio do not want to absorb the fees.
http://www.dbs.com.sg/personal/cards/card-services/payment-plans
Lastly, you can search for iStudio in some old threads bundling screen protectors with Apple products (iPhone or iPad, forget which one) to sell. Meaning if you want to buy the Apple products you must the very expensive screen protectors or bundles which would cost much less if you buy from other stalls or shops.
