Nowadays, name card without personal handphone number and calling the Store number on the card will direct you to the H Call center. When i met my SA in Taka, she directly gave his number and told me to whatsapp her so that she can save my number. From then on we had a good communication and also i order on whatsapp and just pick up my orders on store, saves time for me and her, easy transaction. You can try to visit her everytime you are getting an item, it will leave an impression whenever you specifically requests to see her.
You can approach the same SA for the exchange however, if the exchange item is not on the same store, say you saw an item at MBS, then it is easier to exchange on the store you saw the item you liked more. As we all know stocks are low and transfer of items between stores may need approval. I did once exchange a bag i bought in Taka, and exchanged it in Liat, no questions, but i did messaged my SA to inform her and also she did acknowledge that they dont have that particular bag in Taka so i can go ahead and exchange at Liat.
As for the spend, dont stress yourself. Even if you hit the minimum spend say in 3 months it still does not guarantee you will be offered a quota bag. Relationship takes time, as the others say, enjoy the journey, but if you really in a rush for that quota bag, rather spending on items you dont love, just to hit the spend, i rather buy it on the open market, there are new Quota bags everyday on Instagram 2021 Stamp with local receipt too! (reputable ones i guess) but of course there will be no other experience than getting your beloved quota bag in store!