Thanks.
Yeah, I did the same, requesting the pest control people to come back within the warranty period to spray again but these creatures are resilient! And I got bitten the next day after the spray. Since the last spray, we have caught 6-7 of them. Thank goodness that I have a helper who cleans and comb the room to eliminate them daily.
Just to share what I managed to find out on the web recently and am trying out right now.
http://gem-touch.weebly.com/
Since I have the same Delphin Vacuum cleaner, I requested that they sell me their solution instead. After one cleaning yesterday (following their instructions and advice), we have managed to "force" the BBs to come out and caught them. As instructed, one cleaning is sufficient to clean out the BBs but due to my experience, I am skeptical so am monitoring and will apply the same cleaning process again if needed.
I hope this is leading to BB-free day soon!